1. Field of the Invention
The present invention relates to a vehicle power transmitting device, and it also relates to a technique of transmitting power through a planetary gear unit.
2. Description of the Related Art
A vehicle power transmitting device for transmitting power from a power source through a planetary gear unit to an output side are well known. For example, Patent Document 1 (JP-A-09-53703) discloses a power train for an electric vehicle as shown in FIG. 6, wherein, in an planet gear portion 1, an electric motor 2 is connected to a sun gear S, a ring gear R is fixed to a case 3, and a carrier CA is connected to both an output gear portion 4 and an oil pump 5. Accordingly, the planet gear portion 1 function as a reduction mechanism to drive the oil pump 5 at a lower rotational speed than the electric motor 2, thereby preventing a degradation of the oil pump that is driven by the electric motor and increasing its durability.
However, according to a carrier-output structure in which the output power is taken out via the carrier as disclosed in Patent Document 1, the planet gear portion 1 and the output gear portion 4 can not be connected, unless 4 they are offset in the axial direction of the planet gear portion 1, as indicated by the dashed line A. This requires a corresponding axial space, and there is a possibility that the power train itself may be upsized axially.
Further, in general, because arranging the oil pump 5 coaxial with the planet gear portion 1 is advantageous for lubricating the planet gear portion 1, the structure is employed in which the planet gear portion 1 and the oil pump 5 are positioned coaxial with each other as shown in FIG. 6. However, according to such a structure, as obvious from FIG. 6, there is a possibility that the power train itself may be further upsized axially. Noted that this problem is heretofore unknown.